Magnetic suspension pumps

ABSTRACT

A magnetically suspended piston pump comprises a cylinder made of cylindrical permanent magnet, a piston made of circular permanent magnet, and a circular magnetic plate located at an end of the cylinder, in which an outer surface of the piston has an identical magnetic polarity with an inner surface of the cylinder, and a surface of the circular magnetic plate towards an inside portion of the cylinder has an identical magnetic polarity with a surface of the piston facing to the circular magnetic plate.

This application claims the benefit of Chinese Patent Application No. 200410051345.6 filed which is explicitly incorporated by reference in its entity.

TECHNICAL FIELD OF THE INVENTION

This invention relates to a piston pump, and more particularly to a magnetically suspended piston pump.

BACKGROUND OF THE INVENTION

In the prior art, a piston pump typically comprises a cylinder, a piston, an inlet valve and an outlet valve located in the cylinder, and a driving mechanism connected to the piston. The driving mechanism usually comprises a crank connecting rod, a vapor device, and a magnetic connecting rod driving device, etc. According to the number of the cylinders or the number of the inlet/outlet valves, the piston pump may be classified as a single-cylinder, a double-cylinder and a triple-cylinder piston pump, or as a single-purpose and a double-purpose piston pump.

The conventional piston pump has disadvantages that it is of a relatively short service life and includes some easily worn-out parts, for a contact between a piston and a pump will lead to abrasion. Particularly, if the pump is kept continuously working for a long time (e.g., 24 hours a day), some parts of the piston pump should be replaced within 2 years. Even the pump made from the best abrasion-resistance materials will be worn or penetrated (diaphragm pump) in the end. Moreover, resistance generated due to the friction or tension between the portions of the pump (especially working at a high speed) gives rise to a low power efficiency of the pump. That is, power exchanging efficiency of the pump is reduced.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a magnetically suspended piston pump having a new configuration, in which a piston of a cylinder is able to work at a magnetically suspended situation without friction, thereby enhancing the power efficiency and the reliability of the pump.

To accomplish the object of the present invention, a magnetically suspended piston pump is provided, comprising a cylinder, a piston, an inlet valve and an outlet valve located in the cylinder, and a driving mechanism connected to the piston, in which the cylinder is made of permanent magnet, and the piston embedded within the cylinder is also made of permanent magnet. In the invention, the magnetic polarity of an outer surface of the piston is the same as that of an inner surface of the cylinder, and a circular magnetic plate is provided at an end of the cylinder, in which a side surface of the circular magnetic plate towards an inside portion of the cylinder has the same magnetic polarity as a surface of the piston facing to the magnetic plate.

According to an embodiment of the present invention, the circular magnetic plate disposed within the cylinder is made of permanent magnet or electromagnet.

According to another embodiment of the present invention, the piston pump comprises a magnetic connecting rod driving device. The cylinder of this embodiment is configured in a double-cylinder structure, which comprises an upper cylinder and a lower cylinder. A magnetically suspended piston located in the upper cylinder is connected to another magnetically suspended piston located in the lower cylinder by a vertical connecting rod. Two circular permanent magnets are provided at the connecting rob, and a pair of electromagnets are provided at two sides of the circular permanent magnets. A group of coils is disposed in each of the electromagnets. The two groups of coils are connected with each other in series.

In the present invention, two electromagnets, which are controlled by an electronic circuit, may be provided at both ends of the inside of the cylinder, respectively. The electronic circuit may comprise a common-mode rejection circuit, a microprocessor control circuit, and a power amplification circuit. A signal generated by the electromagnets for indicating a variation of the magnetic field is transmitted to the microprocessor control circuit through the common-mode rejection circuit. The microprocessor control circuit generates a response to the signal for driving the power amplification circuit, and then an output signal of the power amplification circuit is transmitted to the electromagnets.

Compared with the prior art, the present invention has the following advantages:

1. The piston fit within the cylinder of the invention works at a magnetically suspended situation without friction between the piston and the cylinder, which thereby renders the piston pump of a higher efficiency and lower power consumption. The power consumption of the invention is generally about half that of a conventional piston pump.

2. The piston pump of the present invention is durable and reliable and in no need of replacement of any parts. Moreover, the piston pump of the invention shows more advantageous when it is employed in an apparatus which needs to work continuously, such as a medical device.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view showing a configuration of the present invention;

FIG. 2 is a schematic view showing a symmetric double-cylinder piston pump of the present invention;

FIG. 3 is a schematic view of an embodiment according to the present invention, in which electromagnets are employed and controlled by an electronic circuit;

FIG. 4 is an electronic circuit diagram of an embodiment according to the present invention, in which the electronic circuit is employed to control electromagnets; and

FIG. 5 is a schematic view showing principles of a magnetic circuit according to the present invention.

DETAILED DESCRIPTION OF THE INVENTION

The present invention and various advantages thereof will be described with reference to exemplary embodiments in conjunction with the drawings.

Refer to FIGS. 1-5, a magnetically suspended piston pump of the present invention mainly comprises a cylinder 1 made of a cylindrical permanent magnet, a piston 2 made of a circular permanent magnet, a circular magnetic plate 3 located at an end of the cylinder 1, an inlet valve 4 and an outlet valve 5 located at another end of the cylinder 1, and a magnetic connecting rod driving device 8.

The piston 2 of the pump is magnetically suspended within the cylinder 1, and fulfills compression or suction of the liquid/gas by moving up and down within the cylinder 1. In practice, the cylinder 1 can be a permanent magnet which generates a uniform magnetic field at an inner surface 100 of the cylinder 1. That is, the intensity of the magnetic field is identical at each of 360 degrees to the inner surface 100. The piston 2 is a circular permanent magnet, and a magnetic polarity of an outer surface 200 of the piston 2 is the same as that of the inner surface 100 of the cylinder 1. For example, each of them is of an N-pole, and therefore between the outer surface 200 and the inner surface 100 a repulsive force will be generated. The repulsive force is identical at each of 360 degrees to the inner surface 100 due to the uniform magnetic field, so that the outer surface 200 of the piston 2 will never contact the inner surface 100. In this manner, the piston 2 is able to avoid contacting the cylinder 1 when moving within the cylinder 1. The principle of the embodiment is to ensure the intensity of the magnetic field to be identical at each of 360 degrees. In the practical operation, such a magnetic field can be easily realized by choosing a proper direction of magnetization. Moreover, there is no need to keep the magnetic field in the upper position equal to the lower position of the inner surface 100. Therefore, it is possible to ensure the piston 2 to be suspended within the cylinder 1 and to move only in an up and down direction. A movement of the piston 2 can be limited to a certain range to further restrict a working travel distance thereof by setting another magnetic field at an opening of the cylinder, which provides the same magnetic polarity as a surface of the piston 2 facing thereto.

According to an embodiment of the present invention, as shown in FIG. 5, fixed circular magnetic plates 301 and 302 are respectively located at two ends 101 and 102 of the cylinder 1. The piston 2 is escaped from over-pumping by setting the circular magnetic plates 301 and 302 respectively having the same magnetic polarity as surfaces 201 and 202 of the piston 2 facing to them. In this manner, the piston 2 can be moved up or down only by a tiny actuated force, for the piston 2 is working at a magnetically suspended state due to the magnetic fields existing around it.

According to another embodiment of the present invention, an alternating magnetic field is applied to both ends of the cylinder to actuate the piston to move up and down to apply work. That is, the piston made of permanent magnet can be moved up and down by a magnetic attractive and repulsive force through alternating the magnetic field.

According to a further embodiment of the present invention, a fixed magnetic field is provided for controlling the movement of the piston. As shown in FIG. 2, a symmetric double-cylinder configuration is employed in the present invention. A circular magnetic plate 303 is located at a bottom portion of an upper cylinder 1001. An inlet valve 41 and an outlet valve 51 are located at an upper end of the upper cylinder 1001 side by side. The magnetic polarity of the circular magnetic plate is the same as that of a surface 261 of the piston 26 facing to the circular magnetic plate, so as to prevent the upper magnetic suspended piston 26 from contacting the circular magnetic plate 303. The piston 26 and the circular magnetic plate always repel each other. Especially, when a distance between them is very short the repulsive force will become great. In fact, the increase of the repulsive force will be in a geometric progression with respect to the decrease of the distance. Therefore, the travel of the piston within the upper cylinder 1001 is limited to a certain range. Moreover, the lower cylinder 1002 has a symmetrical configuration to the upper cylinder 1001. An inlet valve 42 and an outlet valve 52 are located side by side at a bottom end of the lower cylinder 1002. A fixed circular magnetic plate 304 is located at a top end of the lower cylinder 1002 to ensure a lower suspended piston 27 within the lower cylinder 1002 free from contacting the fixed circular magnetic plate 304. The upper suspended piston 26 and the lower suspended piston 27 are connected with each other through a connecting rod 8. When the connecting rod 8 is driven to move upward, the upper cylinder 1001 works at a compression situation while the lower cylinder 1002 is at a suction situation. The suspended piston 27 will never collide with the top end of the cylinder 1002 due to the limitation of the fixed magnet ring 304. In the same way, when the connecting rod 8 is driven to move downward, the upper cylinder 1001 works at a suction situation while the lower cylinder 1002 is at a compression situation. The suspended piston 26 will never collide with the bottom end of the cylinder 1001 due to the limitation of the fixed magnet ring 303. Therefore, the piston pump of the present invention is extremely quiet during operation for there is no noise caused by the mechanical contact even in a high speed operation.

Based on the above description, it is understood that no mechanical friction is generated by the piston pump of the present invention, since there is no mechanical contact during operation, which prevents the parts of the pump from being worn-out theoretically and makes the service life quite long. In the manufacturing, it is possible to ensure a high pressure (small instantaneous leakage) generated during operation, if only an outer diameter of the magnetically suspended piston matches an inner diameter of the magnetic cylinder. And, the pressure of applying work is constant when the cylinder is kept unchanged. When abrasion occurs due to some problems, a gap between the piston and the cylinder is increased, and thereby a relative pressure will be decreased. Therefore, it is very important to design a proper gap and a proper pressure for the piston pump with a small gap and an excellent precision also means a high cost and vice versa (The pressure, i.e., the power is mainly determined by an outside actuated force, however. For the same power, the sealing performance may be a key factor to determine the working pressure). The connecting rod 8 outside the cylinder is able to move up and down, thereby providing an actuated force, through magnetic fields generated by two circular permanent magnets 9 and 10. Two electromagnets 11 and 12 are respectively provided at two sides of the permanent magnets 9 and 10; forming an angle of 180 degrees from each other. A group of coils 13 are embedded within the electromagnet 11 and a group of coils 14 are embedded within the electromagnet 12. The two group of coils 13 and 14 are connected with each other in series (that is, when providing with electric power, the electromagnets placed with an angle of 180 degrees will generate an identical polarity). In this manner, when supplied with AC power, the magnets will move up and down with high efficiency due to the balanced force. Moreover, the magnets are able to avoid over-pumping due to the limitation of the configuration of the electromagnets. Consequently, the entire magnets are in a magnetically suspended situation without contacting any supporting parts, i.e., without causing mechanical friction. The invention can really provide a magnetically suspended piston pump.

Referring to FIGS. 3 to 4, according to another embodiment of the present invention, the pump just has one cylinder 1005, which has a configuration similar to the cylinder 1 as described above, except that the magnets disposed at both ends of the circular cylinder are not permanent magnets but electromagnets 15 and 16. In this embodiment, the attractive and repulsive force can be altered by varying a current direction of the electromagnets 15 and 16. However, this configuration is somewhat complicated for it is controlled by an electronic circuit. Two magnetic sensors are provided at both ends of the cylinder 1005 to monitor a position of the piston 205, so as to control a direction of the current. In practice, electromagnets 15 and 16 are able to serve as the sensors (referring to FIG. 4, the electromagnets 15 and 16 can be used both as the magnetic field generators and the sensors).

The working principle of the above-mentioned pump is described as follows: When power is applied, a microprocessor circuit 18 generates an oscillating signal. Since, at the first period, it is not known what the initial position of the suspended piston 205 is, the suspended piston 205 is driven to move up or down. When the suspended piston 205 moves close to an end of the cylinder 1005, the magnetic field near the end is changed, which causes the sensors located near the end generating a signal. The signal is received by the microprocessor control circuit 18 through a common-mode rejection circuit 17, and the microprocessor control circuit 18 then generates a response command to indicate a power amplification circuit 19 to reverse the current direction. Therefore, the magnetic field is reversed, and the pump is turned to a compression situation from a suction situation and vice versa. In this way, the magnetically suspended piston 205 can be driven to move up and down to apply work. Since the electromagnets 15 and 16 respectively located at two ends of the cylinder 1005 are of opposite magnetic polarity (i.e., one is employed for generating an attractive force while the other one is employed for generating a repulsive force, but the magnetic polarity is switched as soon as the current direction is reversed). Thus, the operation provides a high efficiency and an excellent precision, and the working pressure or the suction force is constant, for it is the volume of applying work not the time that determines when to reverse the current direction. The volume of compression/suction work is identical for full-load and empty-load cases. Without being affected by friction, the compression/suction force of the piston pump is constant, which is especially useful for some cases requiring high precision (such as in the medical field). The piston pump of the present invention is easy to operate with a simply configuration, high efficiency, constant pressure, and excellent precision.

Moreover, the magnetically suspended piston pump of the present invention can be employed in various fields, such as in air pump or fluid field, for it is completely oil-free and rubber-free without causing abrasion of the components thereof. For example, the piston pump of the present invention is suitable to be used in some cases of corrosive gas, for the permanent magnet is durable against chemicals. If the piston pump is used in the case of corrosive fluid, the permanent magnet can be protected against the corrosion by coating with a corrosion proof material, such as a nylon coating. In practice, various materials may be used to manufacture the pump of the invention according to operational situations. 

1. A magnetically suspended piston pump, which comprises a cylinder made of permanent magnet; a piston made of permanent magnet, the piston being provided within the cylinder and driven by a driving mechanism; and an inlet valve and an outlet valve disposed at the cylinder, wherein an outer surface of the piston has an identical magnetic polarity with an inner surface of the cylinder, a circular magnetic plate is provided at an end of the cylinder, and a surface of the circular magnetic plate facing to an inside portion of the cylinder has an identical magnetic polarity with a surface of the piston facing to the circular magnetic plate.
 2. The piston pump according to claim 1, wherein the circular magnetic plate is disposed within the cylinder, and is made of permanent magnet or electromagnet.
 3. (canceled)
 4. The piston pump according to claim 1, wherein the driving mechanism comprises two electromagnets provided at both ends of the cylinder, respectively, and an electronic circuit controlling the two electromagnets to generate an alternating magnetic field around them, which thereby drives the piston to move.
 5. (canceled)
 6. The piston pump according to claim 4, wherein the electronic circuit comprises a common-mode rejection circuit, a microprocessor control circuit, and a power amplification circuit, wherein a signal for indicating a variation of the magnetic field is transmitted to the microprocessor control circuit through the common-mode rejection circuit, the microprocessor control circuit generates a response to the signal for driving the power amplification circuit, and then an output signal of the power amplification circuit is transmitted to the electromagnets.
 7. The piston pump according to claim 6, wherein the signal is generated by two magnetic sensors provided at both ends of the cylinder.
 8. The piston pump according to claim 6, wherein the signal is generated by the two electromagnets.
 9. The piston pump according to claim 1, wherein the driving mechanism comprises a connecting rod connected to the piston.
 10. The piston pump according to claim 1, wherein the cylinder is configured to generate a uniform magnetic field so that the intensity of the magnetic field is identical at each of 360 degrees to the inner surface of the cylinder.
 11. The piston pump according to claim 1, wherein two fixed circular magnetic plates are respectively provided at both ends of the cylinder, the fixed circular magnetic plates are configured to have the same magnetic polarity as surfaces of the piston facing to them, respectively.
 12. A magnetically suspended piston pump, which comprises: an upper cylinder and a lower cylinder made of permanent magnet, each having an inlet valve and an outlet valve; an upper piston and a lower piston made of permanent magnet and provided within the upper cylinder and the lower cylinder, respectively; and a driving mechanism connected to the upper piston and the lower piston, wherein an outer surface of the upper piston has an identical magnetic polarity with an inner surface of the upper cylinder and an outer surface of the lower piston has an identical magnetic polarity with an inner surface of the lower cylinder; an upper circular magnetic plate is provided at a bottom portion of the upper cylinder and a lower circular magnetic plate is provided at a top portion of the lower cylinder; and a surface of the upper circular magnetic plate facing to an inside portion of the upper cylinder has an identical magnetic polarity with a surface of the piston facing to the upper circular magnetic plate and a surface of the lower circular magnetic plate facing to an inside portion of the lower cylinder has an identical magnetic polarity with a surface of the piston facing to the lower circular magnetic plate.
 13. The piston pump according to claim 12, wherein each of the two cylinders is configured to generate a uniform magnetic field so that the intensity of the magnetic field is identical at each of 360 degrees to the inner surface of the cylinder.
 14. The piston pump according to claim 12, wherein each of the two circular magnetic plates is made of permanent magnet or electromagnet.
 15. The piston pump according to claim 12, wherein the driving mechanism comprises a connecting rob connected between the upper piston and the lower piston, two circular permanent magnets provided at the connecting rob, a pair of electromagnets respectively provided at two sides of the circular permanent magnets forming an angle of 180 degrees from each other, and two groups of coils respectively disposed in the electromagnets and connected in series with each other. 